Method of improving the sensitivity characteristics of emulsions



Patented Nov. 5, 1946 mitten UNITED STATES "PATENT OFFICE METHOD OFIMPROVING THE SENSITIVITY CHARACTERISTICS OF EMULSIONS William F. Smithand Robert E. Stauffer, Rochester, N. Y., assignors to Eastman KodakCompany, Rochester, N. Y., a corporation of New Jersey No Drawing.Application August 26, 1943,

- Serial No. 500,087

9 Claims.

This invention relates to photographic emulsions and particularly to amethod for increasing the speed and contrast of such emulsions.

In Trivelli and Smith U. S. application Serial No. 500,088, filedconcurrently herewith, a method is described for increasing thespeed orcontrast of gelatino-silver halide emulsions. This method involves theincorporationof 'hydrazine or-its derivatives such as hydrazides orsemi-carbazides in emulsions to efiect an improvement in the sensitivitycharacteristics of the emulsion. The Trivelli and Smith applicationdescribes hydrazine derivatives of the general formula:

be used in conjunction with the hydrazine compounds of the Trivelli andSmith application to yield marked increases in the efiects obtained withthe hydrazine compounds. These added compounds are cationic, oniumcompounds including cationic cyclammonium quaternarysalts or sulfoniumsalts which do not act as-desensitizers for the emulsion.

The cationic cyclammonium quaternary salts or sulfonium salts are usedtogether with the hydrazine compound either in the emulsion or thedeveloper. Both the hydrazine compound and. the quaternary salt orsulfoniurn salt may be in the emulsion or both may be in the developeror one may be in the emulsion and the other in the developer.

The following compounds are representative of cationic cyclammoniumquaternary salts or sulfonium salts which are suitable for use accordingto our invention: i 1

BASIC OPTICAL SENSITIZING DYES =Cyanz'ne dyes3,3-diethylthiazolinocarbocyanine iodide (Brooker, U. S. Patent 3,3-diethyl-Q-methylselenacaabgrgggiiine iodide (White, U. S. Patent3,3-diethyloxacarbocyanine iodide (Hamer, J. Chem. 800., 1927,

page 2796) O=GH l C2115 C2115 I V 3,3'-diethyloxacyanine iodide (Fisher& Hamer, J. Chem. Soc., 1934, 40 I page 962) v 0 I s \OH GZCHTO21.201143 icH 3 N N 32115 C2/H5\I3,3-diethyl-4-methyloxathiazol0carbocyanine iodide (Mees, U. S. Patent2,159,565)

ammo

3,8 -dimethyl-9 ethyl 4,5,4 ,5 dilaenzothiacarbobyanine bromide(Brooker, U. S. Patent 1,969,444)

1,1-di methyl-9-aza-2,2-cyanine iodide (Mees, The Theory of thePhotographic Process, 1942, page 1025)3,3-diethyl-4,5,4,5-dibenzothiacyanine iodide (British Patent 504,821)

3,3 diethylthiacarbocyanine iodide (Harr er, J. Chem. Soc, 1927, page2796) 3,3'-diethyl-9-methylthiacarbocyanine iodide (Homer, J. Chem.800., 1928, page 3160) N C2115 211s 1,1-diethy1-2,2-cyanine iodide(Mees, The Theory of the Photographic Process, 1942,. page 1002) Pyrroledyes Styryl dyes NON-SENSITIZING QUATERNARY SALrs CuHa-CH2(3H2 Blfl-Phenylethyl-a-picolinium bromide CeHsCH2CH2 Ifl-Phenylcthyl-a-picoliniumiodide p-Tert. butylphenoxyethoxy-ethylpyridinium perchlorate C104 CHz-O-CHaCHrO-CH: C104N,N"ethylene-dioxymethyl pyridinium perchlorate SULFONIUM SALTS CH3 CvHnN onyl dimethyl sulionium p-toluene sulfonate The pyrrole dyes aredescribed in Brooker and Sprague U. S. Patent 2,298,731. Thenon-sensitizing quaternary salts are referred to in Carroll U. S. Patent2,271,623 and Carroll and Spence U. S. 2,334,864.

It will be seen that the compounds suitable for use according to ourinvention include cyclammonium quaternary salts of the sensitizing andnon-sensitizing types. All of thes compounds are of the cationic type,that is, possess a complex cationic structure. In the case of theoptical sensitizers, the efiect which is produced according to ourinvention is separate and independent from optical sensitization as willbe shown in the specific examples below.

The mechanism of the action of the cationic quaternary salts appears torest on the adsorption of the positive charges of the cationic agents tothe negatively charged silver halide grain with resultant reduction ofthe induction period during development with negatively chargeddeveloper ions. Such induction effects are especially prominent withalkaline p-hydroquinone developers.

Our invention will now be illustrated by reference tov the followingspecific examples:

EXAMPLE 1,

A fine-grain gelatino-silver bromoiodide emulsion was prepared and toportions of the emulsion were added hydrazine dihydrochloride and 3,3diethylthiazolinocarbocyanine iodide, sepa rately and in combination.Coatings wer made of these emulsions and, after drying, these coatingswere exposed ona photographic sensitometer to the light transmitted froma 3200? K. tungsten source by a Wratten No. 35 filters The. first: of

gamma thesecoating's was the plain emulsion without additions; thesecond coating contained 4 grams of hy- -'drazine dihydrochloride 'per4000 cc. of wet emulsi'oni thethird coating consisted of the originalemulsion with 100 mg. of '3,3'-diethy'lthiazolinocarbocyanine iodide andthe fourth coating consisted of the original emulsion with 4 grams ofhydrazine dihydrochloride and 100 mg. of 3,3- diethylthiazolinocar-bocyanine iodide added per 4000 cc. of Wet emulsion.

Since the carbocyanine dye added to the third and fourth coatingssensitizes to green light, all of the coatings were exposed through aWratten No. 35 filter, which absorbs green light, in order to test theefiect of the sensitizing dye on the emulsion independently of itsoptical sensitizing effect. The filter limited the exposure of all ofthe emulsions to the blue spectral region.

All of the coatings were processed after exposure for 1.5 minutes at 65F. in a developer known as Kodak D-8 developer which has the followingcomposition: j

Hydroquinone grams 45 Sodium hydroxide do 27.5 Sodium sulfite(desiccated) do 90 Potassium bromide do Water to iiters 1 The speed andcontrast of each of the images was then determined and the followingresults were obtained.

emulsion was prepared and. to portions of its were added separately andin combination, 4-(o-to1yl) semicarbazide and 3,3-diethylthiazolinocarbocyanine iodide. These portions were then coated and dried. The firstcoating consisted of the plain emulsion without additions; the secondcoating the emulsion to which had been added 100 mg. of l-(o-tolyl)-semicarbazide per 200cc. of wet emulsion; the third coating theoriginal emulsion to which har been added 5 mg. of 3,3-

diethylthiazolinocarbocyanine iodide per 200 cc. of wet emulsion and thefourth coating the orgiinal emulsion to which'had been added 100 mg. of4-(o-tolyl) -semicarbazide and 5 mg. of3,3'-diethylthiazolinocarbocyanine iodide per 200 cc. of wet emulsion.These emulsions were exposed through a Wratten No. filter as in the caseof Example 1 and were developed in the same manner. The followingresults were obtained:

g Contrast Fog Emulsion without additions 2.28 4.9 0.05 Emulsion-H00 mg.4-(otolyl)-semicarbazide 1.95' 6.8 .05 Emulsion+5 mg.3,3-diethylthiazolmo carbocyanine iodide 2. 22 4. 2 .04 Emulsion+l00 mg.4-(O-tolyD-sem1carbazide and 5 mg. 3,3-diethylth1azolmocarbocyanineiodide 2. 82 23. 0 07 V] I EXAMPLE3 H A fine-grain gelatino-silverchlorobromide emulsion was prepared and to portions of it were added4-(o-tolyl) -semicarbazide and a mixture of the semicarbazide andfi-phenylethyl-a-picolini um bromide.

The first portion consisted of the plain emulsion without additions, thesecond portion consisted. of the original emulsion to which had beenadded mg. of 4-(o-tolyl) -semicarbazide per 200 cc. of wet emulsion andthe third portion consisted of the original emulsion to which had beenadded 100mg. of 4-(o-tolyl)- semicarbazide and 200 mg. of B-phenylethylpicolinium bromide per 200 cc. of wet emulsion. These three portionswere separately coated "and dried-and exposed on a photographicsensitometertolight transmitted from a 3200" K. tungsten source. TheWratten filter was omitted because the quaternary salt used in this casewas not an optical sensitizer. The emulsions were processed as inExample 1 and the following results were obtained: r r

ggg Contrast Fog Emulsion without additions 5.35 5. 9 0. 05 Emulsion+l00mg. 4-(o-toIyD-Semicarbazide 5.10 6.1 .05 Emulsion+l00 mg.4-(o-toly1)-semicarbazide and 200 mg. B-phenylethyl.-i-

plcolinium bromide 6.45 10.6 .09

EXAMPLE 4 A fine-grain gelatinoesilver chlorobromide emulsionwasprepared and to portions of it were addedphenylmethyl-dimethylacethydrazido ammonium chloride and a mixture ofthe hydrazide and 3,3-diethyl-9-methylthiacarbocyanine iodide; The firstportion consisted of'the plain emulsion without additions, the secondportion consisted of the original emulsion to which had been added 200milligrams of phenylmethyl-dimethylacethydrazido ammonium chloride per200 cc. of wet emulsion and the third portion consisted of the originalemulsion to which had been added 200 milligrams of the hydrazide and 5milligrams of 3,3'-diethyl-9-methylthiacarbo cyanine iodide per 200 cc.of wet emulsion. These three portions were separately coated and driedand exposed on a photographic sensitometer to light transmitted from a3200 K. tungsten source through a Wratten No. 35 filter. These emulsionswere developed as in the case of Example 1 and the following resultswere obtained:

ag Contrast Fog Emulsion without additions 6.05 5.5 0.07 Emulsion+200mg. phenyl-methyldimethylacethydrazido ammonium chloride. as. 70 8. 5 06Emuls1on+200 mg. phenyl-methyldimethylacethydrazido ammonium 'chlorideand 5 mg. 3,3-diethyl9-methyl thiacarbocyanine iodide 9.00 13.3 07

.ylthiacarbocyanine iodide :per. 200cc.v of,-wet Y emulsion. Uponexposure and development as in Example 4, the following results wereobtained:

EXAMPLE 6 Three emulsion coatings were prepared as in Example 4,thefirst being the emulsion without additions, the second containing 20milligrams of phenyl succinic dihydrazide per 200 cc. of wet emulsionand the third containing 20 milligrams of phenyl succinie dihydrazideand 8 milligrams of 3,3'-diethylthiazolino carbocyanine iodide per200.00. of wet emulsion. These coatings were exposed and developed as inExample 4 and the following results were obtained:

lO/i speed Contrast Fo Emulsion without additions 1.62 i. 4 0. 06Emulsion-[40 mg. plienyl succinic dihydrazide 2. 05 6. 07 Emulsion+20mg. phenyl succinic dihydrazide and 8 milligrams3,3-diethylthiazolino-carbocyanine iodide 2. 00 7. 5 .06

r the emulsion.

.sensitometer.

EXAMPLE 7 The following example serves to illustrate'the action of thecyclammonium quaternary salt in the developer with the hydrazinecompoundin To a fine grain gelatino-silver chlorobromide emulsion therewas addedll.5 grams per 4000 cc.

of 4-(o-tolyl) semicarbazide.

This emulsion was coated and dried and portions of the coating wereexposed for one second to a 3000 K. light source on .a photographic Theseparation portions of the coatings were then developed for two minutesat 65 F. in Kodak D-8 developer oflthe formula stated in Example 1, bothwithout and with addition of varying amounts of3,3-diethylthiazolinocarbocyanine iodide. The amount of this quaternarysalt was varied between 8.3 mg. and 33.3 mg.-per liter of developer andthe following sensitometric results were obtained:

Amount of quaternary salt gg Contrast Fog 13.0 6. 0 0.05 8 3 mg. perliter 14.0 6. 0 05 16.7 mg. per liter 16.0 9. 8 .05 33.3 mg. per literl7. 5 l0. 0 .05

EXAMPLE 8 grams of hydrazine dihydrochloride per liter of D-B developer;the second developer contained 10 milligrams of hydrazinedihydrochloride and 16 zmilligrams of 3,3-diethylthiazolinocarbocyanineiodide per liter of 13-8 developer and the third developer contained 10milligrams of hydrazine dihydrochloride and 33 milligrams of 3,3-diethylthiazolinocarbocyanine iodide per liter of 13-8 developer. Thefollowing sensitometric results were recorded with the variousdevelopers.

'g Contrast Fog D-B 2. 60 4.8 0.14 D8+l0 mg. hydrazine dihydrochlorideper 1000 cc 3. 60 9.0 .16 D8+l0 mg. hydrazine dihydrochloride+ 16 mg.3,3-diethylthiazolinocarbocyanine iodide/1000 cc 3. 10.4 l6 D-8+10 mg.hydrazine dihydrochloride+ 33 mg. 3,3-diethylthiazolinocarbocysnineiodide/1000 cc 9. 10 15. 5 25 The acid optical sensitizing dyes such aserythrosine and the neutral optical sensitizers such as the merocyanineseither cause-losses in the elfects produced by the hydrazine compoundsor are inert sensitometrically from this standpoint. Accordingly, onlythe basic optical sensitizing dyes are suitable for use according to ourinvention.

The compounds which are used according to our invention should notdesensitize thev emulsion. Certain basic dyes are desensitizers and,therefore, are not satisfactory for use according to our invention.Phenosafranine, for example, is a basic dye which is a well knowndessensitizer. Although it might be classed as an optical sensitizingdye, it is better known for its desensitizing properties and istherefore, excluded from the scope of our invention. The structuraldistinction between those basic dyes which sensitize a photographicemulsion and those which desensitize an emulsion is described by Mees inThe Theory of the Photographic Process, 1942, pages 10401047.

The non-sensitizing quaternary salts such as p-phenyl-ethyl-a-picoliniumbromide, which are listed above, have been used as supersensitizers insilver halide emulsions. However, our eifect is not believed to be asupersensitization since not all supersensitizers enhance the eifectproduced by the hydrazine compounds. For example, 6-methoxyquinoline hasbeen used as a supersonsitizer but is inert with respect to improvementof the sensitometric characteristics in the manner contemplated by ourinvention.

The eifect produced according to our invention' is noticeable on varioustypes of silver halide emulsions such as silver bromide, silverchlorobromide and silver bromoiodide emulsions.

We have referred to thesensitivity characteristics of the emulsion. Bysensitivity characteristics we mean the speed and contrastcharacteristics as indicated by the characteristic curve of theemulsion.

Where we refer to actinic radiation we intend to include visible light,as well as ultra-violet light, infra-red light, X-rays, and gamma rays,and also charged particles, such as a-rays, ,e-rays, and cosmic rays.

We claim:

1. The method of producing an image inan undeveloped silver halidedeveloping-out emulsion, which comprises exposing said emulsion anddeveloping it with a hydroquinone developing "agent at a pH of at leastapproximately 9.5 in

the presence of a compound selected from the group consisting ofhydrazine compounds of the general formula:

where at least two Rs are hydrogen atoms and when less than 4 Rs arehydrogen atoms the remainder are carbon radicals, and the salts of saidcompounds, and also in the presence of an onium compound selected fromthe group consisting of non-desensitizing cationic cyclammoniumquaternary salts and sulfonium salts.

, 2. The method of improving the sensitivity characteristics withrespect to actinic radiation of a silver halide photographic layer,which comprises exposing an undeveloped silver halide emulsion layer toactinic radiation and developing it with a hydroquinone developing agentat a pH of at least approximately 9.5 in the presence of a compoundselected from the group consisting of hydrazine compounds of the generalformula:

where at least two He are hydrogen atoms and when less than 4 Rs arehydrogen atoms the remainder are carbon radicals, and the salts of saidcompounds, and also in the presence of an onium compound selected fromthe group consisting of non-desensitizing cationic cyclammoniumquaternary salts and sulfonium salts.

3. The method of improving the sensitivity characteristics with respectto actinic radiation of a silver halide photographic layer, whichcomprises exposing an undeveloped silver halide emulsion layer toactinic radiation and developing it with a hydroquinone developing agentat a pH of at least approximately 9.5 in the presence of a compoundselected from the group consisting of hydrazine compounds of the generalformula:

where at least two Rs are hydrogen atoms and when less than 4 Rs arehydrogen atoms the remainder are carbon radicals, and the salts of saidcompounds and also in the presence of a non-desensitizing cationiccyclammonium quaternary salt.

4. The method of improving the sensitivity characteristics with respectto actim'c radiation of a silver halide photographic layer, whichcomprises exposing an undeveloped silver halide emulsion layer toactinic radiation and developing it with a hydroquinone developing agentat a pH of at least approximately 9.5 in the presence of a compoundselected from the group consisting of hydrazine compounds of the generalformula:

where at least two Rs are hydrogen atoms and when less than 4 Rs arehydrogen atoms the remainder are carbon radicals, and the salts of saidcompounds, and also in the presence oi a emulsion layer to actinicradiation and developing it with a hydroquinone developing agent at a pHof at least approximately 9.5 in the presence of a compound selectedfrom the group consisting of hydrazine compounds of the general-formula:

NHz NH-R where R is selected from the class consisting of hydrogenandCONHCeH5, and the salts of said compounds, and also in the presenceof a nondesensitizing cationic cyclammonium quaternary salt.

6. The method of improving the sensitivity characteristics with respectto actinic radiation of a silver halide photographic layer, whichcomprises incorporating in a gelatino-silver halide emulsion a hydrazineand an onium compound selected from the group consisting ofnondesensitizing cationic cyclammonium quaternary salts and sulfoniumsalts, coating the emulsion on a support, exposing the emulsion toactinic radiation, and developing it at a pH of at least approximately9.5 in the presence of said hydrazine and onium compound.

7. The method of improving the sensitivity characteristics with respectto actinic radiation of a silver halide photographic layer,which'comprises incorporating in a gelatino-silver halide emulsion ahydrazine and a non-desensitizing cationic cyclammonium quaternary salt,coating the emulsion on a support, exposing the emulsion to actinicradiation, and developing it at a pH of at least approximately 9.5 inthe presence of said hydrazine and quaternary salt.

8. The method of improving the sensitivity characteristics with respectto actinic radiation of a silver halide photographic layer, whichcomprises exposing said layer to such radiation and developing it at apH of at least approximately 9.5 in a solution containing a photographicdeveloping agent, a hydrazine compound selected from a group consistingof compounds of the general formula:

tion, and developing it at a pH of at least 9.5 in

a developing solution containing a photographic developing agent and anonium compound selected from the group consisting of non-desensitizingcationic cyclammonium quaternary salts and sulfonium salts.

WlLLIAM F. SMITH. ROBERT E. STAUFFER.

